/*
 * $Id: Threads.java 185 2011-12-20 07:30:09Z tweea $
 * Copyright(C) 2011 Matrix
 * All right reserved.
 */
package net.matrix.util;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 线程相关工具类.
 */
public class Threads
{
	private static Logger LOGGER = LoggerFactory.getLogger(Threads.class);

	private Threads()
	{
	}

	/**
	 * sleep等待,单位毫秒,忽略InterruptedException.
	 */
	public static void sleep(long millis)
	{
		try{
			Thread.sleep(millis);
		}catch(InterruptedException e){
			LOGGER.warn("thread interrupted.");
		}
	}

	/**
	 * 按照ExecutorService JavaDoc示例代码编写的Graceful Shutdown方法.
	 * 先使用shutdown, 停止接收新任务并尝试完成所有已存在任务.
	 * 如果超时, 则调用shutdownNow, 取消在workQueue中Pending的任务,并中断所有阻塞函数.
	 * 另对在shutdown时线程本身被调用中断做了处理.
	 */
	public static void gracefulShutdown(ExecutorService pool, int shutdownTimeout, int shutdownNowTimeout, TimeUnit timeUnit)
	{
		pool.shutdown(); // Disable new tasks from being submitted
		try{
			// Wait a while for existing tasks to terminate
			if(!pool.awaitTermination(shutdownTimeout, timeUnit)){
				pool.shutdownNow(); // Cancel currently executing tasks
				// Wait a while for tasks to respond to being cancelled
				if(!pool.awaitTermination(shutdownNowTimeout, timeUnit)){
					LOGGER.error("Pool did not terminate");
				}
			}
		}catch(InterruptedException ie){
			// (Re-)Cancel if current thread also interrupted
			pool.shutdownNow();
			// Preserve interrupt status
			Thread.currentThread().interrupt();
		}
	}

	/**
	 * 直接调用shutdownNow的方法, 取消在workQueue中Pending的任务,并中断所有阻塞函数.
	 */
	public static void normalShutdown(ExecutorService pool, int timeout, TimeUnit timeUnit)
	{
		try{
			pool.shutdownNow();
			if(!pool.awaitTermination(timeout, timeUnit)){
				LOGGER.error("Pool did not terminate");
			}
		}catch(InterruptedException ie){
			Thread.currentThread().interrupt();
		}
	}
}
